A man being born from a women. The circle of life and a pagan view. A god being born of a goddess is another pagan view specifically Wiccan. A demi god being born of a women, sounds like Hercules again pagan Star dust encompesses everything and some stars have multiple rings around them.

Beyond the various concepts of birth, the ring around a pentagram often represents the interconnected nature of the elements and the divine, or the spirit, or whatever you wish to call that which is not physical.

Circles within the circle, depending on what else is inscribed in the pentagram along with it, often indicate this as well.

A pentagram is a symbol. A pattern. Humans have always looked for "patterns" in everything! Flower petals, the shape of cones,but especially in the stars and the planets.
In the clear desert air, a few planets, certainly Mars and Venus, can be seen with the naked eye. And one planet was very peculiar! Venus! When Man developed the telescope,Venus began to look even more peculiar! First of all it rotated in the opposite direction of the other planets.But of much more interest was its orbital path! The planets seemed, to the old astronomers, to go around in a circle; all except Venus. After many years of study, watching, and carefully noting,it was discovered that the orbit of Venus did not go in a circle; it moved in straight lines! After noting that the planet took about 8 years for the orbit to complete, the astronomers made a startling discovery. The orbit of Venus forms a perfect "shape" in the sky. A Pentagram.
Don't take my word for this! Look it up!